Unfortunately, this is a terse answer, as I haven't done this myself before, but Net::Netmask should do the trick for you, I'd think.

use Net::Netmask;

$block=new Net::Netmask("10.0.2.0/24");
if ($block->match("192.168.1.2")) { ... }

[download]
Update: added code example 

-><- -><- -><- -><- -><-
All things are Perfect
    To every last Flaw
    And bound in accord
         With Eris's Law
 - HBT; The Book of Advice, 1:7

In reply to Re: Checking IP's with an IP/mask by jwest
in thread Checking IP's with an IP/mask by strredwolf

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